Refining is the process of treating raw hydrocarbon (e.g. crude oil) and its conversion into lighter, higher octane number components. Crude oil is the starting point for many diverse products, such as motor oil and gasoline, but also clothes, medical equipment, electronics, vitamin capsules, tires, etc.
During the course of refining crude oil, the crude oil and resultant process streams may be subjected to separation (e.g. distillation), conversion (e.g. thermal cracking), purification, and various other treatments. Distillation is often the first step to separate the crude oil into unfinished products, which occurs by applying heat (as high as 750 F) to a stream of crude oil. The bottom product of each distillation tower may feed the next distillation tower. The tower bottom products are typically the components of the crude oil or refinery fluid that are still liquid at such elevated temperatures.
During distillation, the higher boiling compounds that may have a higher molecular weight and/or greater viscosity are separated from lower boiling compounds. After removal of the distillate, the resulting bottoms may be subjected to further processes, such as conversion and/or purification. Conversion processes include fluidized catalytic crackers, cokers, hydrocrackers, and the like. The conversion processes ‘convert’ or alter the structure of the hydrocarbon chain within a particular process stream.
The atmospheric or vacuum tower bottoms (VTBs), also known as ‘resid’, are the final bottom products from distillation. The VTBs may be processed in cokers to be upgraded into gasoline, diesel, and gas oil. The VTBs are the heaviest material in the refinery. Some VTBs are sold into the paving asphalt market as a blend component. The VTBs (a heavy hydrocarbon material) may also be further converted into more valuable products by using high temperature to break the hydrocarbon chains within the VTBs by using a coker, such as a delayed coker.
Unfortunately, as the viscosity of the process stream (e.g. a heavy hydrocarbon in a non-limiting embodiment) increases, the handling, moving, and/or further refining of the process stream becomes more difficult. For example, the VTBs may even solidify and block fluid movement within a process stream in some circumstances.
Diluents are typically added to the hydrocarbon fluid or stream to dilute the fluid and thereby decrease the viscosity to prevent solidification and/or increase fluid movement within the process stream. Common or traditional diluents are also hydrocarbon-based, such as a distillation tower cut, e.g. naphtha, which may be used for dilution and transportation of the heavy hydrocarbon. However, such diluents are difficult to handle and are highly regulated.
It would be desirable if less diluent could be added to the hydrocarbon fluid to decrease the viscosity of the hydrocarbon-based fluid. It would also be desirable if agents could be devised for decreasing the viscosity of the hydrocarbon-based fluid that are more environmentally friendly alternatives to traditional diluents.